Switchgear protections Archives

41. A transmission line is protected by

Inrush protection

Distance protection

Time graded and current graded over current protection

Both (B) and (C)

Detailed SolutionA transmission line is protected by

42. Arc in a circuit behaves as

a capackive reactance

an inductive reactance

a resistance increasing with voltage rise across the arc

a resistance decreasing with voltage rise across the arc

Detailed SolutionArc in a circuit behaves as

43. Distance relays are generally

split-phase relays

reactance relays

impedance relays

none of the above

Detailed SolutionDistance relays are generally

44. The material used for fuse must have

low melting point and high specific resistance

low melting point and -low specific resistance

high melting point and low specific resistance

low melting point and any specific resistance

Detailed SolutionThe material used for fuse must have

45. Insulation resistance of high voltage circuit breakers is more than

1 mega ohms

10 mega ohms

100 mega ohms

500 mega ohms

Detailed SolutionInsulation resistance of high voltage circuit breakers is more than

46. The single phasing relays are used for the protection of

single phase motors only

two phase motors only

two single phase motors running in parallel

three phase motors

Detailed SolutionThe single phasing relays are used for the protection of

47.

Load flow

Load flow and short-circuit

network analyzer is used to solve problems of A. Load flow B. Load flow and short-circuit C. Load flow and stability

Load flow, short-circuit and stability

Detailed Solution

48. A differential relay measures the vector difference between

two currents

two voltages

two or more similar electrical quantities

none of the above

Detailed SolutionA differential relay measures the vector difference between

49. To reduce short circuit fault currents are used.

reactors

resistors

capacitors

none of the above

Detailed SolutionTo reduce short circuit fault currents are used.

50. Protection by fuses is generally not used beyond

20 A

50 A

100 A

200 A

Detailed SolutionProtection by fuses is generally not used beyond